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Abstract: In this study, the original tourmaline and beryl mineral samples have been collected from a Brazilian pegmatite. The objective of this study was to examine the adsorption behavior of uranyl from aqueous solution on Brazilian cyclosilicate samples. The cyclosilicate samples were characterized by elemental analysis, X-ray diffraction, and nitrogen adsorption–desorption. The ability of these minerals to remove the U(VI) from aqueous solution was followed by a series of adsorption isotherms, using a batchwise process. The adsorption maximum was determined to be 2.95 and 2.60×10−4molg−1 for beryl and tourmaline mineral samples, respectively. The energetic effects caused by radionuclide cation adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such U(VI)–OH interactions. [Copyright &y& Elsevier]

Abstract: Imogolite is an important paracrystalline hydrous aluminosilicate with a unique nanofiber structure. The synthetic imogolite sample was used for organofunctionalization process with 2-mercaptothiazoline and 2-mercaptobenzimidazole. Due to the increment of basic centers attached to the pendant chains, the metal adsorption capability of the final chelating materials, was found to be higher than is precursor. The ability of these materials to remove rubidium from aqueous solution was followed by a series of adsorption isotherms at room temperature and pH 4.0, in batch adsorption experiments in order to explain the adsorption mechanism. The maximum number of moles adsorbed was determined to be 17.89×10−2, 29.89×10−2, and 30.55×10−2 mmolg−1 for IMO, IMOMBI, and IMOMTZ, respectively. In order to evaluate the aluminosilicate samples as adsorbents in dynamic system, a glass column was fulfilled with aluminosilicate samples (1.0g) and it was fed with 1.9×10−3 moldm−3 rubidium at pH 4.0. The energetic effects caused by metal cations adsorption were determined through calorimetric titrations. The enthalpic and entropic values indicated the existence of favorable reaction between rubidium-nitrogen and sulfur center atoms on pendant chain covalent bonded to the inorganic backbone. [Copyright &y& Elsevier]

Abstract: The objective of this study is to examine the adsorption behavior of Sumifix Brilliant Orange 3R textile dye from aqueous solution on smectite sample, an abundant Amazon clay. The original smectite clay mineral has been collected from Amazon region, Brazil. The compound 2-aminomethylpyridine was anchored onto smectite surface by heterogeneous route. The ability of these materials to remove the Sumifix Brilliant Orange 3R textile dye from aqueous solution was followed by a series of adsorption isotherms, using a batchwise process. The maximum number of moles adsorbed was determined to be 1.26 and 2.07mmolg−1 for natural and modified clay samples, respectively. The energetic effects caused by dye cations adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such dye–nitrogen interactions. [Copyright &y& Elsevier]

Abstract: Al-kanemite was synthesized by using inorganic salts as a source for silicon and aluminum in the hydrothermal synthesis of the material. The resulting solid was used as hosts for functionalization of polar n-alkylamine molecules of the general formula H3C(CH2) n −NH2 (n =1 to 5) in aqueous solution. The compound was calorimetrically titrated with amine in 1,2-dichloroethane, requiring three independent operations: (i) titration of matrix with amine, (ii) matrix salvation, and (iii) dilution of the amine solution. From those thermal effects the variation in enthalpy was calculated as: (−6.81, −7.76, −8.97, −9.94, and −11.83)kJ·mol−1, for n =1 to 5, respectively. The exothermic enthalpy values reflected a favorable energetic process of amine-host functionalization in 1,2-dichloroethane. The original and modified Al-kanemite samples were characterized by elemental analysis, scanning electron microscopic (SEM), and nuclear magnetic nuclei of silicon-29 and carbon-13. The negative Gibbs free energy results supported the spontaneity of all these functionalization reactions. The positive favorable entropic values, as carbon chain size increased, are in agreement with the free solvent molecules in the solution, as the amines are progressively bonded to the crystalline inorganic matrix at the solid/liquid interface. [ABSTRACT FROM AUTHOR]

Abstract: The synthetic imogolite sample was used for organofunctionalization process with 2-mercaptothiazoline (MTZ). The compound 2-mercaptothiazoline was anchored onto imogolite surface by heterogeneous route. Due to the increment of basic centers attached to the pendant chains the dye adsorption capability of the final chelating material, was found to be higher than is precursor. The ability of these materials to remove methylene blue from aqueous solution was followed by a series of adsorption isotherms at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 40.32×10−2 and 65.13×10−2 mmolg−1 for IMO and IMOMTZ, respectively. The energetic effects caused by dye cations adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such methylene blue-nitrogen and sulfur interactions. [Copyright &y& Elsevier]

Abstract: The compound N-[3-(trimethoxysilyl)propyl]diethylenetriamine (MPDET) was anchored onto Amazon kaolinite surface (KLT) by heterogeneous route. The modified and natural kaolinite clay samples were characterized by transmission electron microscopy (TEM), scanning electron microscopic (SEM), N2 adsorption, powder X-ray diffraction, thermal analysis, ion exchange capacities, and nuclear magnetic nuclei of 29Si and 13C. The well-defined peaks obtained in the 13C NMR spectrum in the 5.0–62.1ppm region confirmed the attachment of organic functional groups as pendant chains bonded into the porous clay. The adsorption of uranyl on natural (KLT) and modified (KLTMPDET) kaolinite clays was investigated as a function of the solution pH, metal concentration, temperature, and ionic strength. The ability of these materials to remove U(VI) from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 8.37×10−3 and 13.87×10−3 mmolg−1 for KLT and KLTMPDET at 298K, respectively. The energetic effects (Δint H, Δint G, and Δint S) caused by metal cations adsorption were determined through calorimetric titrations. [Copyright &y& Elsevier]

Abstract: The original smectite clay mineral has been collected from Amazon region, Brazil. The compound 2-aminomethylpyridine (AMP) was anchored onto Amazon smectite surface by heterogeneous route. The natural (SMC) and modified (SMCAMP) smectite samples were characterized by elemental analysis, scanning electron microscopy, N2 adsorption, X-ray diffraction, and silicon-29 and carbon-13 nuclear magnetic resonance. Due to the increment of basic centers attached to the pendant chains, the metal adsorption capability of the final chelating material, was found to be higher than the precursor. The ability of these materials to remove Cr(VI) from aqueous solution was followed by a series of adsorption isotherms at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 1.16 and 1.87mmolg−1 for SMC and SMCAMP, respectively. In order to evaluate the clay samples as adsorbents in dynamic system, a glass column was fulfilled with clay samples (1.0g) and it was fed with 2.0×10−4 moldm−3 Cr(VI) at pH 4.0. The energetic effects caused by metal cation adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such Cr(VI)–nitrogen interactions. [Copyright &y& Elsevier]

Abstract: The original sepiolite clay mineral has been collected from Amazon region, Brazil. The compound 2-aminomethylpyridine (AMP) was anchored onto Amazon sepiolite surface by heterogeneous route. The natural (SPT) and modified (SPTAMP) sepiolite samples were characterized by elemental analysis, SEM, N2 adsorption, and nuclear magnetic nuclei of 29Si and 13C. The well-defined peaks obtained in the 13C NMR spectrum in the 0–160ppm region confirmed the attachment of organic functional groups as pendant chains bonded into the porous clay. The ability of these materials to remove As(V) from aqueous solution was followed by a series of adsorption isotherms at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 7.26×10−2 and 11.70×10−2 mmolg−1 for SPT and SPTAMP, respectively. In order to evaluate the clay samples as adsorbents in dynamic system, a glass column was fulfilled with clay samples (1.0g) and it was fed with 2.0×10−2 mmoldm−3 As(V) at pH 4.0. The energetic effects caused by metal cations adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such As(V)–nitrogen interactions. [Copyright &y& Elsevier]

Abstract: The compound N1-[3-(trimethoxysilyl)propyl]diethylenetriamine was anchored onto Amazon kaolinite surface by heterogeneous route. The modified and natural kaolinite samples were characterized by transmission electron microscopy, scanning electron microscopic, X-ray diffraction, and nuclear magnetic nuclei of 29Si and 13C. The well-defined peaks obtained in the 13C NMR spectrum in the 5.0–62.1ppm region confirmed the attachment of organic functional groups as pendant chains bonded into the porous clay. The ability of these materials to remove U(VI) from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature and pH 4.0. The kinetic parameters analyzed by the Lagergren and Elovich models gave a good fit for a pseudo-second order reaction with k 2 values 16.0 and 25.1mmolg−1 min−1 ranges for natural and modified kaolinite clays, respectively. The energetic effects caused by metal ion adsorption were determined through calorimetric titrations. [Copyright &y& Elsevier]

Abstract: The compound 5-amino-1,3,4-thiadiazole-thiol was anchored onto analogue of heulandite by heterogeneous route. The original (HEU) and modified heulandite (HEUATT) samples were characterized through elemental analysis and nuclear magnetic nuclei of carbon-13 and silicon-29. The ability of these materials to remove Mn(II), Zn(II) and Pb(II) from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation. To achieve the best adsorption conditions the influence of pH and contact time were investigated. Based on the capacity of adsorption of HEUATT to interact with metal ions, the following results were obtained 13.0, 10.1 and 7.4mmolg−1 for Pb(II), Zn(II) and Mn(II), respectively, reflecting a maximum adsorption order of Pb(II)>Zn(II)>Mn(II). The energetic effects caused by metal cation adsorption were determined through calorimetric titrations. [Copyright &y& Elsevier]

Abstract: The compound 5-amino-1,3,4-thiadiazole-thiol (ATT) was anchored onto an Amazon kanemite surface (K) by homogeneous and heterogeneous routes. Both kanemite modification methodologies resulted in similar products, named K CTT and K ATT, respectively. The modified and natural kanemite samples were characterized by textural analysis, FT-Raman, and nuclear magnetic nuclei of 29Si and 13C. Elemental analysis proved that the matrix K ATT presented a higher ATT immobilization than K CTT, with values 1.42 and 1.38mmolg−1, respectively. NMR and FT-Raman confirmed the immobilization of ATT on both surfaces. The ability of these materials to remove thorium(IV) from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 7.48×10−3, 9.82×10−3, and 12.94×10−3 mmolg−1 for K, K CTT, and K ATT, respectively. The energetic effects (Δint H°, Δint G°, and Δint S°) caused by metal cation adsorption were determined through calorimetric titrations. [Copyright &y& Elsevier]

Abstract: Diquite (D) and bentonite (B) mineral samples from the Amazon region, Brazil, were modified by MTTZ derivative (5-mercapto-1-methyltetrazole) using heterogeneous route. These materials were characterized by textural and elemental analysis, transmission electron microscopy (TEM), power X-ray diffraction and 13C NMR spectroscopy. The chemically modified clay (DMTTZ and BMTTZ) samples showed modification of its physical–chemical properties including: specific area 41.4 (B) to 398.5m2 g−1 (BMTTZ) and 25.0 (D) to 178.8m2 g−1 (DMTTZ). The adsorption experiments performed under batch process with Th(IV) concentration, pH and contact time as variables. The ability of these materials to remove thorium from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature and pH 2.0, with variable concentration of Th(IV). The maximum number of moles adsorbed was determined to be 10.45×10−2 and 12.76×10−2 mmolg−1 for DMTTZ and BMTTZ, respectively. The energetic effects (Δint H°, Δint G° and Δint S°) caused by thorium cation adsorption were determined through calorimetric titrations. [Copyright &y& Elsevier]

Abstract: An analogue of heulandite was synthesized by using inorganic salts as a source for silicon and aluminum in the hydrothermal synthesis of the material. The resulting solid was modified by organofunctionalization with 1,4-bis(3-aminopropyl)piperazine and subsequent reaction with methylacrylate in a heterogeneous route. The original (HEU) and modified silicate (HEUAPPMA) samples were characterized by textural analysis, SEM, and nuclear magnetic nuclei of 29Si and 13C. The chemically modified silicate sample showed modification of its physical–chemical properties including specific area 459.0–978.8m2 g−1. The ability of this material to remove nickel(II), cobalt(II), and copper(II) from aqueous solutions was followed by a series of adsorption isotherms adjusted to a Sips equation. The quick adsorption process reached the equilibrium before 10, 15, and 20min for Cu(II), Ni(II), and Co(II), respectively, with maximum adsorptions at pH 4.0. Based on the capacity of adsorption of HEUAPPMA to interact with metal ions, the following results were obtained 12.9, 9.8, and 7.5mmolg−1 for Cu(II), Ni(II), and Co(II), respectively, reflecting a maximum adsorption order of Cu(II)>Ni(II)>Co(II). The energetic effects caused by metal cation adsorption were determined through calorimetric titrations. [Copyright &y& Elsevier]

Abstract: The montmorillonite clay sample from amazon region, Pará State, Brazil, was used for intercalation process with pyridine (P) and organofunctionalization with 3-aminopropyltriethoxysilane (APS). The montmorillonite-P/APS shows variation of d001 values, by changing d001 from 1.15 to 2.10nm. The original and modified samples were used for mercury cation adsorption from aqueous solution at room temperature and pH 6.0. The energetic effect caused by mercury cation adsorption was determined though calorimetric titration at the solid–liquid interface and gave a net thermal effect that enabled the calculation of the exothermic values and the equilibrium constant. [Copyright &y& Elsevier]